When I bought my house, the front landscaping had the mesh fabric and river rock. I'm sure at one point it looked nice, but this is my opinion of river rock and mesh. It's AWFUL! First of all, although the mesh may help at first, dirt will collect on top of it, seeds WILL sprout, and then the tiny roots will work their way down through the mesh. Then, try to pull those weeds, grass, etc. and not pull the mush up, too! Also, the rocks will work their way into the soil without the mesh or plastic, so you really do need something below them. I know plastic is not the choice, but I would use it before the mesh for the reasons I stated. I love the look of the river rock, and it's easier to blow the leaves off of it in the fall (than say mulch). If you are using perennials that will not spread, and are larger plants or shrubs, you might be fine with the rock, as you won't be messing with it once the area is planted. Another downfall is if you plan to put annuals in there, the rock is much harder to move around than mulch, and if you don't use the same hole for an annual you may have used last year, the old hole will be open for weeds, and you will have to cut a new hole.
I ended up removing all the river rock, and put it on my driveway. However, since the ponds have been built, I have slowly scooped up the rock and used it in the waterfall and stream, as a more natural look to the larger rocks.
Another "con" for rock is it's more expensive than mulch, and harder to move around, much heavier. But, in the end, if that's the look you want, then I say go for it! You will figure out how to deal with any bad effects as you go. Good luck!